Image processing devices such as network-capable printers, scanners and copiers are-becoming increasingly popular at a rapid rate as network infrastructures are built.
These network-capable image processing devices are classified into two types, namely (1) a type in which a network function is incorporated within the image processing device, i.e., a type in which a network control function (network controller) is incorporated as part of the controller of the image processing device, i.e., and (2) a type in which the network function is incorporated as an extension of the image processing device, i.e., a type in which network support is provided by inserting a control device having a network control function (network controller) into an expansion slot or connector of the image processing device. Both types of image processing devices are so adapted that the peripheral device such as a printer or scanner is connected to the network controller that is connected to the network.
These network-capable image processing devices are required to have not only the original communication function for communicating print data or scan data but also a configuration management function and troubleshooting management function possessed by a network manager, a network information management function and functions for supporting additional functions. The configuration management function is for configuring the network system and managing addresses and resources. The troubleshooting management function is for detecting network system failures, analyzing and reporting the failures and effecting recovery. The network information management function is for performing network management, namely management of network load and management of performance. An example of an additional function is a function for configuring another peripheral processing device connected via the network.
A Simple Network Control Protocol (SNMP) is utilized to implement these functions. Management information in a network device is managed in the form of a database referred to as a Management Information Base (MIB). In SNMP, an SNMP-equipped network manager acquires or sets the values of MIB variables (described later) by an agent which manages each network device. This allows the above-mentioned functions to be implemented.
FIG. 14 is a conceptual view illustrating the structure of an MIB. As shown in FIG. 14, the MIB has a tree-like data structure in which all nodes are uniquely numbered. The numbers in the parentheses in FIG. 14 are node identifiers. For example, the identifier of a node 1401 in FIG. 14 is 1. Since the identifier of a node 1402 is 3 and this is subordinate to node 1401, it is written 1.3. Similarly, the identifier of a node 1403 is written 1.3.6.1.2. Such an identifier of a node is referred to as an object identifier, and each node is referred to as an MIB variable.
In FIG. 14, a node 1404 is one at the vertex of an object group referred to as a standard MIB with which a device managed by SNMP is equipped as a standard. The details of the structure of an object subordinate to such a node are stipulated in RFC1213 Management Information Base for Network Management of TCP/IP-based Internets: MIB-II.
A node 1405 is one at the vertex of an object group referred to as a printer MIB with which a printer managed by SNMP is equipped as a standard. The details of the structure of an object subordinate to such a node are stipulated in RFC1759 Printer MIB.
A node 1406, which is referred to as a private MIB, is one at a vertex where an enterprise or organization, etc., defines its own MIB. A node 1407, which is referred to as enterprise extension MIB, is one at a vertex where an enterprise among private MIBs implements its own extension. For example, “1602” is assigned to Canon, Inc. as an enterprise number in order that it may define itself. A node 1408, which is a vertex for defining Canon MIB as Canon's own MIB, is situated under the node 1407 signifying an enterprise. The object identifier of the vertex node of Canon MIP is 1.3.6.1.4.1.1602.
An agent is incorporated within an image processing device that is a network device or is mounted on a network controller externally connected to the image processing device. A network controller is an externally attached network interface card, by way of example. The management information (MIB) also is managed by the network controller. If a network device is an image processing device having multiple functions, the database of the MIB of the peripheral device connected to this network device, e.g., the database of a printer MIB or host-resource MIB, also is managed in the network controller.
By virtue of this arrangement, a network device can be made the object of management by an SNMP-equipped network manager. In accordance with SNMP, a network manager can acquire information concerning, or change the status of, a controlled network device belonging to the same community as that of the network manager. For example, a network manager can send a network device a message containing desired MIB variables, can acquire a character string being displayed on the liquid crystal display device of a printer, and can change the default paper-feed cassette.
In such case the network controller in the network device that has received a message analyzes the content of the message. If the content of the message is acquisition of information specific to the peripheral device connected to the network controller, then the network controller acquires information from the pertinent peripheral device via a specific communication interface between itself and the peripheral device. The network controller further converts the acquired information to a format decided by SMNP and then responds to the network manager.
Thus, in the prior art, the network controller must manage also the MIB of the peripheral device that is connected to it. For example, in a case where a plurality of peripheral devices have been combined, as in the manner of a printer and scanner, all of the MIBs relating to these peripheral devices must be managed by the network controller.
Consequently, in a case where a single network controller is capable of being connected to multiple peripheral devices, it is required that the network controller manage all of the MIBs relating to these peripheral devices. For example, there are instances where a network controller is connectable to different model printers A and B, and there are occasions where a network controller is connectable to a printer, scanner and facsimile machine all of which provide different functions. In such cases it is required that all of the MIBs relating to the connectable peripheral devices be managed by the network controller. A problem which arises is that the network controller needs to be furnished with a very large-capacity memory in order to store these databases.
Another problem is that since communication interfaces between the network controller and the peripheral devices connected to it are specific to the peripheral devices, the network controller must support all of these communication interfaces.
If in such case a peripheral device connectable to a network controller is added on anew, the network controller itself or the control software executed by the network controller must be updated in order to support the interface between the network controller and the new peripheral device.